1. Field of the Invention
The present invention relates generally to a fan device with oil-retaining bearing, and more particularly to a fan device with oil-retaining bearing, in which the oil-retaining bearing is securely disposed in the bearing hole and the operation of the shaft will not be affected due to the press fit and the difficulty in controlling the glue dispensing process.
2. Description of the Related Art
Currently, electronic information produces (such as computers) have been more and more popularly used. The electronic information industries and technologies rapidly develop on the demand of consumers. There is a trend to enhance the execution/operation speed of the electronic products and increase the access capacity of the electronic products. As a result, the components in the electronic information produces often generate high heat in high-speed operation.
With a computer mainframe taken as an example, most of the heat is generated by the central processing unit (CPU) of the computer mainframe. In the case that the heat is not dissipated in time, the temperature of the CPU will rise to cause deterioration of the execution performance of the CPU. When the heat accumulates to an extent higher than the tolerance limit, the computer will crash or even burn out. Moreover, in order to solve the problem of electromagnetic radiation, the computer mainframe is generally enclosed in a computer case. Therefore, it has become a critical issue how to quickly dissipate the heat generated by the CPU and other heat generation components.
In general, a heat sink and cooling fan are disposed on the CPU to dissipate the heat generated by the CPU. Several radiating fins are disposed on one side of the heat sink. The surface of the other side of the heat sink (free from any radiating fin) is in direct contact with the CPU. Accordingly, the heat can be conducted to the radiating fins and quickly dissipated by way of radiation. The cooling fan serves to cooperatively forcedly drive airflow to quickly dissipate the heat.
Please refer to FIGS. 1A and 1B. FIG. 1A is a sectional assembled view of a conventional cooling fan with oil-retaining bearing in one aspect. FIG. 1B is a sectional assembled view of a conventional cooling fan with oil-retaining bearing in another aspect. The cooling fan 1 mainly has a fan base seat 11. A bearing cup 111 is disposed on the fan base seat 11. An oil-retaining bearing 12 is disposed in the bearing cup 111. A fan impeller 13 is assembled on the fan base seat 11. The fan impeller 13 has multiple blades 131 annularly arranged on outer circumference of the fan impeller 13. A shaft 132 extends from an inner side of the fan impeller 13. The shaft 132 is fitted through the shaft hole 121 of the oil-retaining bearing 12 and latched and located therein. When the cooling fan 1 operates, the shaft 132 stably rotates within the oil-retaining bearing 12. The oil-retaining bearing 12 is fixedly disposed in the bearing cup 111 in two manners. FIG. 1A shows a first way to fix the oil-retaining bearing 12 in the bearing cup 111. That is, a glue dispensing process is performed between the oil-retaining bearing 12 and the bearing cup 111. In the glue dispensing process, the glue 14 may flow through the gap between the oil-retaining bearing 12 and the bearing cup 111 to the shaft hole 121. As a result, when the shaft 132 rotates within the oil-retaining bearing 12, the shaft 132 will make noise and may clog. FIG. 1B shows a second way to fix the oil-retaining bearing 12 in the bearing cup 111. That is, the outer circumference of the oil-retaining bearing 12 is tightly fitted in the inner circumference of the bearing cup 111 by means of press fit. When the oil-retaining bearing 12 is tightly fitted into the bearing cup 111, the shaft hole 121 of the oil-retaining bearing 12 will be contracted to compress the shaft 132. This will affect the normal assembly of the shaft 132 in the shaft hole 121 and the operation of the shaft 132 or even lead to clog of the shaft 132.
According to the above, the conventional cooling fan has the following shortcomings:    1. The glue dispensing process is hard to control so that the shaft will make noise and may clog.    2. When the oil-retaining bearing is tightly fitted into the bearing cup, the shaft hole of the oil-retaining bearing will be contracted to compress the shaft. This will affect the normal assembly of the shaft or even lead to clog of the shaft.